Is Cheney Next?

Could a guilty verdict for a former aide bring further criminal scrutiny of Vice President Dick Cheney?

"Yes," said Sol Weisenberg, a former deputy independent counsel to former Whitewater special prosecutor Kenneth Starr.

As a federal jury deliberates the fate of former Cheney chief of staff I. Lewis "Scooter" Libby, several watchers agree. If the jury decides Libby knew he was lying to investigators, it could spur investigators to explore further whether Cheney was involved in conspiring to obstruct justice, they believe.

Libby's lawyers did not immediately respond to a request for comment. The office of the vice president declined to discuss the matter.

At issue is a conversation between the two men in the fall of 2003, soon after the federal probe began to identify who leaked CIA officer Valerie Plame's identity.

Libby recalled the conversation from the stand, "I told the vice -- you know, there was -- the president said anybody who knows anything should come forward or something like that...I went to the vice president and said, 'You know, I was not the person who talked to Novak,'" according to the "National Journal," whose reporter Murray Waas attended the trial and was the first to note the possible trouble a guilty verdict could cause for the vice president.

"[H]e [said] something like, 'I know that,'" Libby continued. "And I said, you know, 'I learned this from Tim Russert.' And he sort of tilted his head to the side a little bit, and then I may have in that conversation said, 'I talked to other -- I talked to people about it on the weekend.'"

"What did you understand from his gesture or reaction in tilting his head?" Fitzgerald asked Libby, according to Waas' account.

"That the Tim Russert part caught his attention," Libby replied. "You know, that he, he reacted as if he didn't know about the Tim Russert thing, or he was rehearing it or reconsidering it or something like that...New, new sort of information. Not something he had been thinking about."

"And did he at any time tell you, 'Well, you didn't learn it from Tim Russert, you learned it from me?'" asked Fitzgerald. "'Back in June you and I talked about the wife working at the CIA?'"

"No," Libby responded, according to Waas.

That brief conversation could be trouble for Cheney, reports Waas, because at the time of the conversation, Cheney "already had reason to know that Libby's account to him was untrue, according to sources familiar with still-secret grand jury testimony," as well as evidence and testimony from the Libby trial.

Of course, an extended Cheney probe may not garner much. "I don't know how much more there would be for Fitzgerald to do," Weisenberg told ABC News. Libby and Cheney were the only parties to the conversation, he noted, so further cooperation from Libby would be the only way to discern its true meaning.

First, Fitzgerald would need to win a guilty verdict for Libby and push for the harshest sentence possible, said Washington, D.C. lawyer Stanley Brand, who has built a practice around defending public officials. Then, he could grant Libby immunity from further prosecution and offer leniency in an effort to coax Libby to say more about the vice president's role, if any, in obstructing his leak investigation.

Even then, it would take a lot more evidence than that one conversation to build a case against the vice president, Brand told ABC News. "A wink and a nod can't be obstruction," he said. "There has to be overt acts and intent."